Leakage current refers to a very small current flowing through a semiconductor component when a PN junction is in cut-off state or when charging of a capacitor is complete, and is also referred to as an Ir leakage current. The leakage current is an inherent feature and an important performance indicator of a semiconductor component, a filter, a power supply, and a capacitor. Due to surface damages of a component, wafer cracks, and the like caused by problems such as vendor process exceptions, raw material contamination, and internal management, a leakage current of the component often exceeds a limit.
When a component is just delivered from the factory, latent problems such as stress, cracks, and contamination may not be directly presented as an abnormal leakage current. In an initial stage of the leakage current, generally functions of a product are not affected directly. Therefore, a leakage current exceeding a limit belongs to a latent defect of the component. After the component experiences power-on, reflow soldering, and thermal shock, air inside the cracks of the component expands or contamination ions rapidly diffuse. Therefore, abnormality of the component occurs, resulting in a leakage current exceeding a limit. As time goes by, under an effect of an environmental factor such as humidity, temperature, and voltage, the leakage current becomes severe gradually, which shortens the service life of the product substantially.
In prior art 1, a test pen is operated manually to probe a component under detection to perform a leakage current test. This manual testing manner is inefficient and consumes a lot of manpower and material resources.
In prior art 2, a leakage current test is performed by using a commercial semiconductor tester (for example, Agilent® 4339B, or the like). As shown in FIG. 1, a nominal voltage is applied between two ends of a component under detection, and an ammeter is used to measure a small current flowing through the component under detection. The leakage current is generally at a 10*E to 9 A level. Therefore, in a common electrical qualification test for a board-mounted component, it is difficult to stably test a leakage current. In addition, this manner is mainly applied to sample inspection and delivery detection in incoming quality control (IQC), batch detection cannot be implemented, and a detection ratio is limited.
Moreover, the foregoing test manners are only intended for testing an isolated component. When the component is surface mounted to a board, leakage current detection may not be performed any longer. When leakage current detection is required, the component needs to be removed from the board before being detected. Consequently, a large number of components subject to a leakage current problem flow into markets, causing a board function failure.